In the anime

Officer Jenny is not a single entity. Rather, there are many Jennys working as police officers across the various regions of the Pokémon world.

Generally, Officer Jennys are brave and determined, but can be ineffective in their police duties. They fight against the likes of Team Rocket, Team Magma, Team Aqua and Team Galactic - among other miscellaneous criminals. Although there are many exceptions, Officer Jenny will generally have Growlithe to use as a police dog.

Although Jennys appear to be identical, there is some minor divergence among them, as evidenced by Brock. Brock is able to recognize different Jennys on numerous occasions; he appears to be the only character who can tell the Officer Jennys apart. The town/region where a certain Jenny comes from can be discerned by the symbol on their hats, which differs depending on location. There seem to be two Viridian Jennys, as during the Indigo League, two Jennys with the same hat symbol (previously stated to belong to the Viridian City Jenny) were seen side-by-side. The Jennys of the Orange Archipelago are outfitted with uniforms of a distinctly lighter blue color. The Unova region is home to Officer Jennys that look distinctly different than those of other regions. The Unova Officer Jennys all have a tan-colored uniform, unlike the other Jennys that wore blue. Additionally, the Jennys of Unova don a much shorter hairstyle.

There is a very distinct parallel between the families of Officer Jenny, Nurse Joy, and Don George. This may indicate some sort of relation or deeper connection. However, the only thing known about the three families is that they are apparently on good terms.

Ash's Squirtle was loaned to an Officer Jenny who fights fires. It is the leader of a group of four other Squirtle known as the "Squirtle Squad", who serve as the local firefighting team.

A young Officer Jenny named Marble appeared in Luxray Vision!. She was in charge of looking for "The Bandit Beauties Three."

When a strange fog started to surround the Skyarrow Bridge, the Officer Jenny of the area attempted to use her Swanna to clear it. However, this didn't work and both Jenny and Swanna quickly left to deal with an emergency.

This Gastly was used by the Jenny on Mandarin Island North. It was able to use its ghost moves to find Butch, Cassidy and their Drowzee, who had brainwashed all of the other Pokémon on the island, being immune to the brainwash itself. It has an unusually high Special Defense, as it was later used to protect Ash from the combined attacks of the controlled Pokémon. Gastly is kept outside its Poké Ball.

During their travels through the Decolora Archipelago, Ash and his friends encountered a group of Water-type Pokémon who were stealing food from their ferry, with Croconaw as their leader. All four Pokémon in the so-called Pirate gang had been abandoned by their Trainers and were distrustful of humans. Ash battled Croconaw and Azumarill with Snivy and Pignite and won, forcing the pirates to hand over what they had stolen. Croconaw then led its friends to save a group of Darumaka that were being swept out to sea, and found it enjoyed rescuing others. As a result, the pirates joined up with Officer Jenny as a Water Rescue Squad.

Azumarill was a powerful and eager member of Croconaw's pirate gang, who had no problems with stealing food from humans. It battled Snivy and Pignite alongside Croconaw but was defeated. However, it did assist in the rescue of the Darumaka before happily joining with Officer Jenny.

Octillery was another powerful member of Croconaw's pirate gang, and would often battle any Pokémon it came across. Like the other Pokémon in the gang, Octillery was abandoned by its Trainer. However, it had a happy ending and also joined Officer Jenny's new squad.

Ducklett, another abandoned water-type Pokémon, was the fourth member of Croconaw's gang and was responsible for keeping the raft they traveled on from drifting away. Ducklett later joined Officer Jenny's squad after participating in the Darumaka rescue.

Trivia

The Officer Jenny of LaRousse City is seen wearing a different uniform to all her counterparts, it being a far more elaborate version than the others (although it does retain the standard coloring and basic design scheme).

Officer Jenny, Nurse Joy and Don George all have Japanese names that begin with the kana ジ, while their English names all start with the same sound, dʒ. They also all happen to be part of a large, extended family.